Morteza Mahjoub or Morteza Mahjoob (Persian: مرتضی محجوب, born March 20, 1980) is an Iranian chess grandmaster.

In September 2005 he won Iranian Chess Championship with the score 9.5 points out of 11.

Mahjoob previously held the world record for simultaneous exhibition, which he set on August 13, 2009.

He walked 18 hours and won 397 of the games, 90 draws and 13 loses.

His record was broken on October 21, 2010 by GM Alik Gershon.